<html>
<body>
<table cellpadding="0" cellspacing="0">
 <tr>
  <td>
   <table style="table-layout: fixed;" cellpadding="0" cellspacing="0">
    <tr>
     <td style="background: lightgreen;">a</td>
    </tr>
   </table>
  </td>
  <td>
   <table style="table-layout: fixed;" cellpadding="0" cellspacing="0">
    <tr>
     <td style="background: lightblue;">b</td>
    </tr>
   </table>
  </td>
 </tr>
</table>
</body>
</html>
